netdev - Re: [PATCH net-next v2 3/7] usbnet: smsc95xx: Don't reset PHY behind PHY driver's back

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Date:   Wed, 4 May 2022 00:21:23 +0200
From:   Andrew Lunn <andrew@...n.ch>
To:     Lukas Wunner <lukas@...ner.de>
Cc:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>, netdev@...r.kernel.org,
        linux-usb@...r.kernel.org,
        Steve Glendinning <steve.glendinning@...well.net>,
        UNGLinuxDriver@...rochip.com, Oliver Neukum <oneukum@...e.com>,
        Andre Edich <andre.edich@...rochip.com>,
        Oleksij Rempel <linux@...pel-privat.de>,
        Martyn Welch <martyn.welch@...labora.com>,
        Gabriel Hojda <ghojda@...urs.ro>,
        Christoph Fritz <chf.fritz@...glemail.com>,
        Lino Sanfilippo <LinoSanfilippo@....de>,
        Philipp Rosenberger <p.rosenberger@...bus.com>,
        Heiner Kallweit <hkallweit1@...il.com>,
        Russell King <linux@...linux.org.uk>,
        Ferry Toth <fntoth@...il.com>
Subject: Re: [PATCH net-next v2 3/7] usbnet: smsc95xx: Don't reset PHY behind
 PHY driver's back

On Tue, May 03, 2022 at 03:15:03PM +0200, Lukas Wunner wrote:
> smsc95xx_reset() resets the PHY behind the PHY driver's back, which
> seems like a bad idea generally.  Remove that portion of the function.
> 
> We're about to use PHY interrupts instead of polling to detect link
> changes on SMSC LAN95xx chips.  Because smsc95xx_reset() is called from
> usbnet_open(), PHY interrupt settings are lost whenever the net_device
> is brought up.
> 
> There are two other callers of smsc95xx_reset(), namely smsc95xx_bind()
> and smsc95xx_reset_resume(), and both may indeed benefit from a PHY
> reset.  However they already perform one through their calls to
> phy_connect_direct() and phy_init_hw().
> 
> Tested-by: Oleksij Rempel <o.rempel@...gutronix.de> # LAN9514/9512/9500
> Tested-by: Ferry Toth <fntoth@...il.com> # LAN9514
> Signed-off-by: Lukas Wunner <lukas@...ner.de>
> Cc: Martyn Welch <martyn.welch@...labora.com>
> Cc: Gabriel Hojda <ghojda@...urs.ro>

Reviewed-by: Andrew Lunn <andrew@...n.ch>

    Andrew